Refillable fuse plug



Oct. 9, 1956 J. I. DURHAM ETAL REFILLABLE FUSE PLUG Filed May 17, 1955FIG.2

FIG. 3

FIG.6

FIGQS I llllll 5 m t n e v n FIG.8

JOHN A. CRE

JAMES DURHAM United States Patent O REFILLABLE FUSE PLUG James IrvineDurham and John A. Cree, Hamilton, Ontario, Canada Application May 17,1955, Serial No. 509,019

3 Claims. (Cl. 200-130) This invention relates to improvements inrefillable fuse plugs of the type wherein the plug contains a ribbonfuse and is threaded for insertion into an electrical socket, and theobject of the invention is to devise a plug which may be very readilytaken apart for the replacement of a burned out fuse.

In carrying out the object of the invention we provide a very practicaland simple plug arrangement consisting of three quickly separableportions which are normally locked in assembly by a manually releasablepawl-like spring clip carried by an outer threaded metal sleeve toengage a notched face on the fuse carrying portion of the plug, suchportion being contained within an insulator cup upon which the metalsleeve is threaded.

Another object of the invention is to releasably secure the ribbon fuseto a contact post contained within the fuse carrying portion and to soform the fuse that its outer end length is clamped between the side faceof the insulator cup and the metal sleeve threaded thereunto.

With the foregoing and other objects in view, as shall appear, theinvention consists of a refillable fuse plug formed and arranged all ashereinafter more particularly described and illustrated in theaccompanying drawing in which:

Figs. 1, 2 and 3 are perspective views of the three separable portionsforming the plug.

Fig. 4 is an inverted plan view of the fuse carrying portion shown inFig. 2.

Fig. is a side view of the assembled fuse plug.

Fig. 6 is a vertical cross-sectional view through the assembled fuseplug.

Fig. 7 is a transverse cross-sectional view through the assembled fuseplug.

Fig. 8 is an inverted plan view of the assembled fuse plug.

Fig. 1 illustrates the fuse containing cup 2 which is generally moldedof insulating material, such as glass, and having a clear face 3 in itstop through which the fuse may be seen. Threads 4 are forme on the sideof the cup together with a groove 5 for receiving the outer end lengthof a ribbon fuse, as shall be hereinafter explained.

Fig. 2 illustrates the fuse carrying portion 6 which is also formed ofinsulating material and dimensioned to fit within the cup 2 with itslower end 7 projecting therefrom, the portion having a flange 8 uponwhich the cup rests. A metal contact post 9 in the form of a strip iscontained within a recess 10 in one side of the portion 6 andconstitutes an electrical connection between a contact face 11 in thebottom face of the lower end 7 and a fuse anchoring terminal screw 20threaded into the upper end of the post. The lower or exposed face ofthe flange is formed with a series of radial serrations or notches 12for engagement by the assembly locking spring clip, as shall beexplained.

Fig. 3 illustrates a metal sleeve 13 having threads 14 formed in itswall, the sleeve being arranged to be threaded into a fuse plugreceiving electrical socket. The lower 2,766,353 Patented Oct. 9, 1956end of the sleeve is formed with an inturned flange 15 which restsagainst the serrated face of the flange 8 when the plug is assembled, asshown in Fig. 6. A pawllike spring clip 16 is secured at one end to theouter face of the flange 15 and is inturned at the other end to freelyproject through an orifice 17 in the flange and to engage one of theserrations in the flange 8 when the sleeve is threaded home upon the cup2.

The serration engaging free end of the clip extends in the oppositedirection to the direction in which the sleeve is turned in beingthreaded home upon the cup, whereby in the final turning and tighteningmovement the free end of the clip clicks over the serrations in apawl-like manner, but prevents the sleeve from unthreading from the cupuntil the end of the clip is manually moved outwardly from serrationengagement. To retain the fuse carrying portion 6 against rotation inthe cup 2 the inside face of the cup is formed with a chord flat 18engageable by the edges of the recess 10.

The ribbon fuse is pre-shaped for placement within the fuse plug andcomprises a bridge piece 19 adapted to extend across the top of theportion 6, being downturned and pierced at one end for reception of theterminal screw 20 and formed at the other end with a U-shaped outer endlength 21 adapted to have its inner leg contained within a groove 22 inthe portion 6 and which is opposite to the groove 18 and its outer legcontained within the groove 5 in the outer face of the cup 2, such legbeing corrugated in registering configuration with the cup threads 14,and by means of which electrical contact is established when the sleeve13 is threaded upon the cup.

When assembled and positioned within a socket, current flows through thefuse which forms a bridge between the contact face 11 and the metalsleeve 13, as in standard practice. Should the fuse burn out it is onlynecessary to remove the plug from the socket, slightly pull the free endof the clip 16 from out of contact with the serration it is engaging andunscrew the sleeve 13 from off the cup 2 to take the plug apart forreplacement of a burned out fuse.

From the foregoing description it will be seen that due to the springclip lock between the sleeve and the portion 6 within the cup that theplug cannot come apart when being unthreaded from a socket, and that byeasing the clip outwardly by a slight pull, the plug may be instantlytaken apart for fuse replacement.

What we claim as our invention is:

1. In a fuse plug, a cup-like body part of insulating materialexteriorly threaded, a fuse carrying member fitted into said part andincluding a flange serrated upon its exposed face and adapted to seatagainst the rim of the cup part and a fuse receiving groove extendingfrom the flange to the inner end of said member, a sleeve of conductingmaterial threaded unto said cup part to retain the fuse carrying memberwithin the part and having a lower portion overlying the serrated faceof the flange, a manually releasable pawl-like element carried by thesleeve to engage the serrated face of the flange to normally retain thesleeve against unthreading turning from off the cup part, a contact postcontained within the fuse carrying member and extending from its exposedface to the vicinity of its inner end, and a fuse extending from theinner end of the contact post to the conducting material sleeve.

2. A fuse plug as defined in claim 1, wherein the fuse is in the form ofa ribbon extending across the inner end of the fuse carrying member anddown the groove in said member and across the rim of the cup part to besandwiched between the outer face of said part and the conductingmaterial sleeve carried thereby.

3. A fuse plug as defined in claim 1 wherein the fuse is in the form ofa ribbon extending across the inner end of the fuse carrying member anddown the side of said member and across the rim of the cup part to besandwiched between the outer face of said part and the conductingmaterial sleeve carried thereby.

References Cited in the file of this patent UNITED STATES PATENTS904,832 Bradley Nov. 24, 1908 4 Brown Oct. 3, 1933 Dalcher Feb. 15, 1938Cree et a1. June 24, 1941 Brus Aug. 15, 1944 Larson May 19, 1953

